Defoaming rinse composition



United States Patent 3,082,172 DEFOAMING RINSE COMPOSITION Norman S. Temple, Newport, and Arthur T. Martin, St. Paul, Minn., assignors to Economics Laboratory, Inc., a corporation of Delaware No Drawing. Filed Apr. 5, 1960, Ser. No. 20,018 5 Claims. (Cl. 252-89) This invention relates to surface active compositions and in particular to rinse agents for use in machine dishwashing.

Machine dishwashing is used in connection with practically all commercial and institutional dining facilities as well as in a rapidly increasing proportion of private homes. In commercial machines, the dishes to be washed are introduced into a zone where detergent solution is sprayed over them, the detergent solution being recycled and used repeatedly and fortified and replenished intermittently. In home machines the detergent is used for only one load of dishes and is then discarded although it too is recirculated during the washing operation. Hence in both types of machines, food soil concentrations in the wash solution of 0.05 to 0.1% or higher are considered to be moderate under average conditions.

lt has been the practice in formulating machine dishwashing detergents to use in the main various combinations of inorganic sodium and potassium salts, such as polyphosphates, silicates, carbonates and basic materials such as sodium and potassium hydroxides. it has not been possible to use effective amounts of well-known organic detergents such as the alkyl aryl sulfonates, alkyl sulfonales, alkanol amides or alkyl aryl pohethers in spray-type mechanical dishwashing detergents because of the foam these materials develop during the washing operation. This foam causes overflow and loss of the wash solution, impairs the mechanical operation of the machine. and lowers the pressure at which the washing fluid is impelled against the utensils to be cleaned. The inorganic materials do not foam themselves and. at low concentrations of food soil (less than 0.01%) perform satisfactorily in mechanical dishwashers. However, with increase in food soil concentration to greater than about 0.1%, foaming becomes a serious problem even with the use of purely inorganic detergent systems. This is because the inorganic detergent systems, being alkaline, can cause some saponification of fatty food soils. This, plus the natural foaming properties of protein food soils, tends to produce foam in the wash tank.

Recently, certain low foaming, organic. nonionic detergents have been made available commercially which can be incorporated in small amounts with inorganic materials in mechanical dishwashing formulations without seriously increasing their foaming tendency. These materials add somewhat to the detergency efficiency of the compound formulation. No known compounds of this type, however, have a pronounced effect of inhibiting foam where heavy food soil loads are present, or in maintaining internal wash pressure at a high level under these conditions.

Wash pressure is defined herein as the pressure registered on a manometer or pressure gauge by a Pitot tube set at the outlet of the wash nozzle. The force of the wash spray against a dish surface is directly proportional to this wash pressure. Since it has been shown that the wash action of the wash spray contributes most to gross soil removal, maintenance of the original wash pressure built into the machine is very important.

Excessive foaming in machine dishwashing has long been a recognized problem and, although billowing foam is an obvious indication of trouble, a real wash pressure problem may exist even without this obvious symptom.

3,082,172 Patented Mar. TS, 1963 For example, an "aerated wash solution," though not so easily detected, may be as serious a problem from the standpoint of washing efficiency as billowing foam. An aerated wash solution," as used herein, is defined as a liquid with many small air occlusions or bubbles dispersed in it as contrasted with foam which, as used herein, is defined as a colloidal dispersion of air in liquid floating on top of the wash solution.

The use of rinse additives in machine dishwashing has developed significantly in the last decade and is now widely practiced. In this connection note the article entitled "Rinse Additives by Dr. John L. Wilson appearing in Soap and Chemical Specialties for February 1958. The modern additives are primarily low foaming, organic, nonionic surfactants which, when incorporated in the rinse water, promote rapid draining and drying and eliminate or minimize spotting and streaking.

Depending upon the type of detergent used in the wash cycle and the food soil concentration of the wash solution, the use of rinse additives can have a profound effect upon wash pressure during the succeeding wash cycle. This is because practically all commercial and home dishwashing machines are so constructed and operated that a portion of the final rinse water accumulates in the wash section due to flow through the feed back systems utilized for keeping the prerinse and wash solutions from becoming too highly contaminated with food soil. For example, some rinse additive formulations when thus admixed with the wash solution. have a tendency to accentuate the foaming problem during the succeeding wash cycle. A high wash pressure can be maintained by use of a detergent composition such as that described in our pending application Serial No. 855,897, filed May 26, 1959, now US. Patent No. 3,048,548, even when using conventional rinse additives. Where conventional machine dishwashing detergents are employed, however, the rinse additives of the present invention have been found to be especially effective in maintaining a high wash pressure during the succeeding wash cycle by inhibiting foaming and/or aeration, or both, of the wash solution in the presence of food soil even at high concentrations. The unique properties of the rinse additives of this invention are apparently due to the incorporation into conventional rinse additive formulations of a small proportion of a polyoxyalitylene glycol mixture consisting of a product which statistically represented has a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains or segments, the hydrophilic chains (segments) consisting of oxyethylene radicals linked one to the other and the hydrophobic chains (segments) consisting of oxypropyiene radicals linked one to the other, said statistically represented product having five such chains (segments) comprising three hydrophobic chains (segments) linked by two hydrophilic chains, the central hydrophobic chain (segment) constituting 30% to 34% by weight of the product, the terminal hydrophobic chains (segments) together constituting 31% to 39% by weight of the product, the linking hydrophilic chains (segments) constituting 31% to 35% by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3000 to 5000.

The polyoxyalkylene glycol mixture is prepared by condensing propylene oxide with water or propylene glycol to form a polyoxypropylene glycol, condensing ethylene oxide with the polyoxypropylene glycol, and then condensing propylene oxide with the oxyethylated polyoxypropylene glycol. The preparation must be carried out in the above order to yield products having the required alternating hydrophobe hydrophiie structure.

The conventional rinse additive formulations into which the polyoxyalkylene glycol mixture is incorporated generally contain a low foaming synthetic organic surfactant or wetting agent of the polyethenoxy nonionic type. These include the oxyethylated polyoxypropylene glycols described in U.S. Patent 2,674,619 to Lundsted and sold commercially as Pluronics," the oxyalkylated partial esters of polyhydric alcohols and fatty acids described in U.S. Patent 2,380,166 and sold commercially as Tweens, the benzyl ethers of alkylphenoxy polyethoxyethanols described in U.S. Patent 2,856,434 to Niederhauser and sold commercially as Triton CF-l0. the polyoxyalkylene surfactants described in U.S. Patent 2,677,700 to Jackson et al., the mixed higher polyoxyalkylene ethers of hexitols described in U.S. Patent 2,673,882 to Griffin, alkylphenoxy polyoxyethylcne ethanols produced by the reaction of an alkylphenol with ethylene oxide and sold commercially as Igepals, and the oxyalkylated glycerols, produced by reaction with glycerol of a mixture of ethylene and propylene oxides, marketed by Dow Chemical Co.

Of the above synthetic organic surfactants, the most frequently employed in conventional rinse additive formulations are the Pluronics, described in U.S. Patent 2,674,619 to Lundsted, and Triton CF-IO described in U.S. Patent 2,856,434 to Niederhauser.

U.S. Patent 2,674,619 describes conjugated polyoxypropylene-polyoxyethylene compounds containing in their structure oxypropylene groups, oxyethylene groups and an organic radical derived from an organic compound containing a plurality of reactive hydrogen atoms. The compounds are prepared by condensing propylene oxide at elevated temperatures and pressures in the presence of an alkaline catalyst with the organic compound containing the reactive hydrogen atoms to prepare a polyoxypropylene polymer of at least 900 molecular weight and then condensing ethylene oxide with this polymer until the polyoxyethylene groups constitute approximately 20-90% of the final compound. Thus the compounds are characterized in that all of the oxypropylene groups are present in polyoxypropylene chains that are attached to the organic radical at the site of a reactive hydrogen atom, thereby constituting a polyoxypropylene polymer, and the oxyethylene groups are attached to the polyoxypropylene polymer in polyoxyethylene chains. The organic compound containing a plurality of reactive hydrogen atoms is exemplified by ethylene glycol, propylene glycol, l-3-butylene glycol, oxalic acid, glycolic acid, mono-, di-, and triethanolamine, butylamine, aniline, resorcinol, diethylmalonate, acetamide, 1,5-pentanediol, glycerine, sucrose, ethylene diamine, and benzenesulfonamide. In these organic compounds the reactive hydrogen atoms are normally activated by being a member of a functional group containing an oxygen atom, a basic nitrogen atom, or a sulfur atom. The low foaming materials are those wherein the polyoxypropylene polymer has a molecular weight of about 900 to 2300 as determined by hydroxyl number, and the polyoxyethylene chains represent about to percent by weight of the final compound.

U.S. Patent 2,856,434 describes compounds having the formula oomcrn) .ocmour.

wherein R is an alkyl group of eight to fifteen carbon atoms and n is an integer from twelve to forty. These compounds are prepared by reacting an appropriate alkyl phenol with ethylene oxide at elevated temperatures and pressures in the presence of an alkaline catalyst and condensing the resulting alkylphenoxypolyethoxyethanol with benzyl chloride or bromide in the presence of a strongly basic inorganic neutralizing agent. The lowest foaming materials are those wherein n is 12 to 20.

Most rinse additive formulations contain one or more constituents in addition to the main surfactant. For instance, some formulations contain ethyl or propyl alcohol. Some contain small proportions of a quat y; some contain coloring matter. Some contain water to provide a concentration or consistency suited to the injection equipment used.

The proportion of the polyoxyalkylene glycol mixture incorporated into the rinse additive formulations of this invention generally ranges from about 10 to 40 percent by weight based upon the weight of the synthetic organic surfactant. The polyoxyalkylcne glycol mixture does not appear to add to the rinsing or sheeting properties of the formulation and in some instances at higher concentrations appears to detract from these properties.

The rinse additive formulations of this invention are added to the rinse Water in an amount sutficient to provide a concentration of about 50 to 250 parts per million.

The rinse additives of this invention and their effectiveness in maintaining wash pressure in machine dishwashing operations in the presence of food soils are illustrated by the following examples. In these examples the polyoxyalkylene glycol product has an intrinsic viscosity of 00815, a molecular weight of 4620, and was prepared by condensing 2262 parts by weight of propylene oxide with 76 parts by weight of propylene glycol to form a polyoxypropylene glycol, then condensing 2301 parts by weight of ethylene oxide with the thus formed polyoxypropylene glycol, then condensing 2436 parts by weight of propylene oxide with the thus formed oxyethylated polypropylene glycol. The central polyoxypropylene hydrophobe segment thus constituted 32.8% by weight of the product, the two polyoxyethylene hydrophile linking segments together constituted 32.5% by weight of the product, and the two polyoxypropylene hydrophobe terminal segments constituted 34.4% by weight of the product. The remaining 0.2% was water. Such a product can be prepared by conventional oxyalkylation procedures as described immediately below.

To a 25 gallon autoclave equipped with a mechanical stirrer there is added 76 grams (1 mole) of propylene glycol and 7.5 grams of powdered caustic soda. The autoclave is then sealed, flushed with nitrogen, heated to C., and placed under vacuum to remove any nitrogen and any moisture. The stirrer is started, the temperature is raised to 130 C. and the propylene oxide xsadmltted to the autoclave. The temperature is maintamed at l25-l30 C. and the pressure is kept at approximately 10 to 15 pounds per square inch. When the addition of 2262 grams of propylene oxide is completed and a vacuum noted on the autoclave, ethylene oxide is begun. When the addition of 2301 grams (52.3 moles) of ethylene oxide is complete and a vacuum again noted in the autoclave, the addition of propylene oxide is commenced again. When this propylene oxide addition is completed, the product is cooled under nitrogen, the caustic soda catalyst is neutralized with sulfuric acid, and the product is separated.

EXAMPLE I A rinse additive was prepared having the following formulation:

EXAMPLE II A rinse additive of this invention was prepared having the following formulation:

55 grams water 5 grams of the polyoxyalkylene glycol mixture described above 40 grams of Tritron CF-lD, a benzyl ether of an alkylphenoxypolyethoxyethanol having an 8 or 9 carbon alkyl substituent and containing 13 or 14 oxyethylene groups described in US. Patent 2,856,434.

EXAMPLE III A rinse additive of this invention is prepared having the following formulations:

50 grams water 10 grams of the polyoxyalkylene glycol mixture described above.

40 grams of lgepal C 230, a nonionic surfactant which is a nonylphenoxypolyethoxy ethanol containing approximately two ethoxy groups.

EXAMPLE IV A rinse additive of this invention was prepared having the following formulation:

55 grams water grams of the polyoxyalkylene glycol mixture described above.

30 grams of a low foaming nonionic surfactant A" comparable to Pluronic L 62 which is an oxyethylatcd polyoxypropylene glycol wherein the polyoxypropylene hydrophobe base has a molecular weight of 1750 and has been reacted with ethylene oxide to provide a polyoxyethylene hydrophile unit representing 20 percent of the total molecule.

grams of a nonionic surfactant B" which is prepared by oxyalkylating glycerol with a mixture of ethylene and propylene oxides to a molecular weight of 2600 and then oxybutylating the intermediate to provide a polyoxybutylene unit representing approximately 33% by weight of the total molecule.

EXAMPLE V A rinse additive of this invention was prepared having the following formulation:

45 grams water 15 grams of the polyoxyalkylene glycol mixture described a ove.

30 grams of nonionic surfactant A described in Example IV i 10 grams of nonionic surfactant B" described in Exampie IV.

EXAMPLE VI A rinse additive of this invention was prepared having the following formulation:

55 grams water 5 grams of the polyoxyalkylene glycol mixture described above.

40 grams of Pluronic L 42, a nonionic surfactant which is an oxyethylated polyoxypropylene glycol wherein the polyoxypropylene hydrophobe base has a molecular weight of 1200 and has been reacted with ethylene oxide to provide a polyethylene hydrophile unit representing percent of the total molecule.

EXAMPLE VII A rinse additive of this invention was prepared having the following formula:

56 grams water 4 grams of the polyoxyalkylene glycol mixture described above.

36 grams of Pluronic L 62" described in Example IV.

4 grams of "Pluronic L 61 which is an oxyethylated polyoxypropylene glycol wherein the polyoxypropylene hydrophobe base has a molecular weight 1750 and has been reacted with ethylene oxide to provide a polyoxyethylene hydrophile unit representing 10% by weight of the total molecule.

Formulations corresponding to Examples I, II and IV through VII and designated Examples IA, IIA, IV-A, V-A, VI-A and VII-A respectively, were prepared in which the polyoxyalkylene glycol mixture described previousiy was replaced with an equivalent amount of water. The formulations of Examples I, II, and IV through VII were compared with the corresponding formulations of Examples I-A, II-A and lV-A through VII-A prepared without the polyoxyalkylene glycol mixture with respect to their effect on wash pressure in the presence of food soil and a conventional machine dishwashing detergent. Tests were carried out in a Hobart UM undercounter machine having a rotating wash arm. The number of revolutions this arm made per minute with clean water at l40-150 F. was considered standard. After this count was made, a food soil consisting of four parts oleomargarine, and one part of powdered milk was added to the wash solution to provide a food soil concentration of about .475%. Then a typical machine dishwashing detergent was added to provide a detergent concentration of about 38%. After one minute the number of revolutions per minute the wash arm made with this wash solution were counted. Next each of the rinse additives described above was added to provide 175 parts per million of rinse additive in the wash solution and after one minute the number of revolutions per minute the wash arm made was counted. The efiiciency of these foam depressing formulations can be determined by the extent to which the final r.p.m. count approaches that of clean From an inspection of the data of Examples II through VII-A in Table I, it can be seen that the rinse additives of this invention, when added to a wash solution containing food soil and a conventional detergent, were efi'ective in increasing the wash pressure significantly. In Example I, Pluronic L 63 was employed having a polyoxyethylene hydrophile unit representing 30 percent of the total molecule. This particular Pluronic is a moderate foamer in and of itself and the polyoxyalkylene glycol mixture apparently was not effective in decreasing the foam caused by the Pluronic.

The formulations described in the specific examples contain appreciable quantities of water. The amount of water present is determined by the type of injection equipment employed to incorporate the rinse additive into the rinse water. Some devices are designed to iniect dilute solutions of the rinse additive while others are designed to iniect essentially percent active material. For use with the former, the rinse additive formulations of this invention generally contain about 35 to 70% water.

Instead of the polyoxyalkylene glycol mixture employed in the specific examples, other polyoxyalkylene glycol mixtures such as those described in the following Table II can be employed.

said statistically represented product having five such chains comprising three hydrophobic chains linked by two hydrophilic chains, the central hydrophobic chain constituting 30% to 34% by weight of the product, the terminal Table II Parts by weight of materials used a on on in prep ring n smiten Refractive Cloud point 0.1%, in Specific Intrinsic M 01.

Propylene Ethylene Propylene index 1% at F. 1110 at gravity viscosity weight.

oxide oxide oxide dynes/cni. added iris added in added in Step1 Step 2 Step 3 lfimploynd in Examples I-NII.

We claim:

l. A rinse additive composition useful in machine dishwashing consisting essentially of a low-foaming, synthetic organic polyethenoxy nonionic surface active agent otherwise useful as a machine dishwashing rinse additive at concentrations throughout the range of 50 to .250 parts per million of rinse water and a small amount sutficient to maintain wash pressure during the succeeding wash cycle of a polyoxyalkylene glycol mixture consisting of a product which statistically represented has a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains, the hydrophilic chains consisting of oxyethylene radicals linked one to the other and the hydrophobic chains consisting of oxypropylene radicals linked one to the other, said statistically represented product having five such chains comprising three hydrophobic chains linked by two hydrophilic chains, the central hydrophobic chain constituting to 34% by weight of the product, the terminal hydrophobic chains together constituting 31% to 35% by weight of the product, the linking hydrophilic chains together constituting 31% to 35% by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3000 to 5000.

2. A rinse additive composition useful in machine dishwashing consisting essentially of a low foaming synthetic organic polycthenoxy nonionic surface active agent otherwise useful as a machine dishwashing rinse additive at concentrations throughout the range of 50 to 250 parts per million of rise water and from about 10 to percent by weight based on the nonionic surface active agent of a polyoxyalkylene glycol mixture consisting of a product which statistically represented has a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains, the hydrophilic chains consisting of oxyethylene radicals linked one to the other and the hydrophobic chains consisting of oxypropylene radicals linked one to the other,

hydrophobic chains together constituting 31% to 39% by weight of the product, the linking hydrophilic chains together constituting 31% to 35% by weight of the product, the intrinsic viscosity of the product being from about 0.06 to 0.09 and the molecular weight of the product being from about 3000 to 5000.

3. The rinse additive composition of claim 2 wherein the synthetic organic polyethenoxy nonionic surface active agent is a conjugated polyoxypropylene-polyoxyethylene compound containing in its structure oxypropylene groups and oxyethylene groups, all of the oxypropylene groups being present in a polyoxypropylene polymer chain having an average molecular weight as determined by hydroxyl number of about 900 to 2300, all of the oxyethylcne groups being attached to the polyoxypropylene polymer chain in polyoxyethylene chains, the oxyethylene groups present constituting 10 to 20 weight percent of the compound.

4. The rinse additive composition of claim 2 wherein the synthetic organic polyethenoxy nonionic surface active agent is a compound of the formula n-Qmomotnnoc mom,

References Cited in the file of this patent UNITED STATES PATENTS Niederhauser et al Oct. 14, 1958 OTHER REFERENCES Pluronic Surfactants as Rinse Aids," publication of Wyandotte Chemicals (F3305), received in U.S. Patent Ofiice January 7, 1957, 4 pages.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,082 172 March 19, 1963 Norman SQ Temple et all" It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 'i'O for "formu la read formulation columns 7 and 8, Table II under the heading "Intrinsic viscosity" for "000185" read 000815 column T line 54 for "rise" read rinse S1gned and sealed this 15th day of October 1963a (SEAL) Attest:

EDWIN L REYNOLDS ERNEST W. SWIDER Attesting Officer Ac t1 ngcommissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,082, 172 March 19 1963 Norman S. Temple et a1 ror a ent requiring co ppeaors in the above numbered patcorrected below.

rrection and that the said Letters Patent should read as Column 5, line 70, for "formula" read formulati on columns 7 and 8, Table II under the heading "Intrinsic viscosi ty" for "00185" read 0,0815 column 7, line 54 for "rise" read rinse Signed and sealed this 15th day of October 1963,

(SEAL) Attest:

EDWIN L REYNOLDS ERNEST W. SWIDER Attesting Officer A c t. i n g Commissioner of Patents 

1. A RINSE ADDITIVE COMPOSITION USEFUL IN MACHINE DISHWASHING CONSISTING ESSENTIALLY OF A LOW-FOAMING, SYNTHETIC ORGANIC POLYETHENOXY NONIONIC SURFACE ACTIVE AGENT OTHERWISE USEFUL AS A MACHINE DISHWASHING RINSE ADDITIVE AT CONCENTRATIONS THROUGHOUT THE RANGE OF 50 TO 250 PARTS PER MILLION OF RINSE WATER AND A SMALL AMOUNT SUFFICIENT TO MAINTAIN WASH PRESSURE DURING THE SUCCEEDING WASH CYCLE OF A POLYOXYALKYLENE GLYCOL MIXTURE CONSISTING OF A PRODUCT WHICH STATISTICALLY REPRESENTED HAS A PLURALITY OF ALTERNATING HYDROPHOBIC AND HYDROPHILIC POLYOXYALKYLENE CHAINS, THE HYDROPHILIC CHAINS CONSISTING OF OXYETHYLENE RADICALS LINKED ONE TO THE OTHER AND THE HYDROPHOBIC CHAINS CONSISTING OF OXYPROPYLENE RADICALS LINKED ONE TO THE OTHER, SAID STATISTICALLY REPRESENTED PRODUCT HAVING FIVE SUCH CHAINS COMPRISING THREE HYDROPHOBIC CHAINS LINKED BY TWO HYDROPHILIC CHAINS, THE CENTRAL HYDROPHOBIC CHAIN CONSTITUTING 30% TO 43% BY WEIGHT OF THE PRODUCT, THE TERMINAL HYDROPHOBIC CHAINS TOGETHER CONSTITUTING 31% TO 35% BY WEIGHT OF THE PRODUCT, THE LINKING HYDROPHILIC CHAINS TOGETHER CONSTITUTING 31% TO 35% BY WEIGHT OF THE PRODUCT, THE INTRINSIC VISCOSITY OF THE PRODUCT BEING FROM ABOUT 0.06 TO 0.09 AND THE MOLECULAR WEIGHT OF THE PRODUCT BEING FROM ABOUT 3000 TO
 5000. 